Display screen or portion thereof with an icon



FIG. 1 is a front view of a first embodiment of a display screen or portion thereof with an icon showing our new design; and,

FIG. 2 is a front view of another embodiment of a display screen or portion thereof with an icon showing our new design.

The broken lines illustrate a display screen or portion thereof and form no part of the claimed design. 

CLAIM The ornamental design for a display screen or portion thereof with an icon, as shown and described. 